The unifying hypothesis of this proposal is that the use of biomaterial scaffolds is critical to the development of successful therapies for spinal cord injury. In the absence of a biomaterial scaffold that can help bridge the injury site, the lack of regeneration promoting substrates in the injured spinal cord limits the efficacy of current drug delivery and cell transplantation approaches. We hypothesize that the biomaterial scaffolds can be used to direct the differentiation of embryonic stem cell-derived progenitor motor neurons (pMNs), present growth factor trophic cues and deliver drugs to overcome the inhibitory nature of the adult spinal cord. Through the use of a biomaterial scaffold we hypothesize that we will be able to present combination therapies necessary to achieve significant regeneration following spinal cord injury. This hypothesis will be tested systematically by addressing the following specific aims, all of which are necessary to achieve the goal of spinal cord regeneration. The aims of this proposal are: (1) to test the hypothesis that growth factor delivery from a fibrin-based biomaterial scaffold will enable the survival and differentiation of embryonic stem cell-derived progenitor motor neurons (pMNs) into motoneurons in an in vitro setting at levels comparable to or better than that observed with traditional differentiation protocols. (2) To test the hypothesis that growth factor delivery from a fibrin-based biomaterial scaffold will enable enhanced survival and differentiation of embryonic stem cell-derived motoneuron progenitors (pMNs) into motoneurons compared with pMN transplantation alone (no scaffold) in the in vivo setting of sub-acute (14 day) spinal cord injury. (3) To test the hypothesis that the combination of a biomaterial scaffold (with growth factor delivery), cell transplantation, and delivery of drugs to overcome the inhibitory cues of the adult spinal cord, will provide a combination therapy that is able to achieve regeneration following sub-acute (14 day) spinal cord injury.